1. Field of the Invention
The present invention generally relates to an apparatus to warm fluids meant to be infused into the body, including blood products, to a desired temperature, approximately the normal body temperature. This apparatus is small, portable, and disposable and is easily used by the care giver without special training.
2. Description of Related Art Including Information Disclosed Under 37 CFR 1.97 and 1.98
Fluid introduced intravenously should be warmed to a temperature approximating normal body temperature to prevent the lowering of core body temperature. Intravenous fluids are normally stored at ambient temperature with some products stored at refrigerated temperatures. Normal core body temperature is 98.6.degree. F. (37.degree. C.), ambient temperature is 75.degree. F. (23.9.degree. C.) and refrigerated temperatures are from 32.degree. F. to 40.degree. F. (0.degree. C. to 4.4.degree. C.). In emergency situations, such intravenous fluids may necessarily be introduced at refrigerated temperatures directly into the body through intravenous (I.V.) tubes. Introduction of such liquids at these refrigerated temperatures, however, presents a substantial risk for injurious chill hypothermia and/or shock to the body.
A variety of devices have been developed to address the issue of the warming of intravenous fluids. Current systems are generally of two types. Bulk warmers require a sufficient period of time to warm the product to a desired temperature and will only warm up a set number of fluid units at a time. Moreover, in order for the bulk warmer to be constantly ready for emergency use, it must be maintained at a proper and set temperature. This requires a system which is bulky, heavy, and/or fixed. Prewarming and holding such fluids, as set forth above, is not practical for certain blood products and pharmaceuticals that are degraded if held at an elevated temperature.
Moreover, the bulk warmers allow the fluid to cool in the line set as it is administered. A bulk warmer system also experiences drawbacks associated with emergency use since it requires prior anticipation of the need for warmed fluid units as well as the number of fluid units which will ultimately be needed. Furthermore, and assuming the aforereferenced conditions are met, fluid units that are warmed and ready for use must move through several feet of tubing in addition to the drip chamber thereby offering substantial time and opportunity for such liquids to cool before entering the body.
The second type are in-line fluid warmers. Previous in-line fluid warmers somewhat address the disadvantages described above except that such in-line systems attempt to warm the fluid in the existing plastic line, which is an inefficient means of heat transfer. Moreover, in-line warming systems are generally limited in volume, e.g., 30-40 millimeters per minute, and require a 120-volt AC power source. Additionally, the accuracy of such a system is only plus or minus 5 degrees. They are also bulky and require significant time to set up.
One such system is known as the Animec Infusion Warmer. It is electrically powered and is a dry warmer that supplies external heat to plastic tubes by an aluminum heating plate. Temperature sensors contact the tubing and regulate the temperature. The plastic tube to be heated can be placed in an S-shaped channel in the heating plate in the warmer. Different size tubes can be used. This unit has several disadvantages. First, the length of tubing being heated is comparatively short. Second, the tubing is contacted by the aluminum plate over only a portion of its surface area. Third, total heating of the heating plate is based only on the output temperature of the fluid. Fourth, different models must be used for different sized tubing. Fifth, it is not portable but requires a 110-volt AC power source. Sixth, it is possible that excessive warming of the fluid can occur. Seventh, it is not a disposable warming unit.